This invention relates to a cooling system for a liquid cooled internal combustion engine and more particularly to a system including a bypass for controlling coolant flow through the system.
Commonly, a pressurized cooling system employs a circulating liquid coolant for cooling an internal combustion engine, including both gasoline and diesel fueled engines. Engine heat is transferred from the engine to the coolant through a coolant jacket surrounding certain parts of the engine. The heat absorbed by the circulated coolant is dissipated by a heat exchanger, generally by a radiator, into the air.
Under most normal operating conditions, an engine only requires nominal coolant flow to maintain proper temperature of internal components. However, under severe conditions, an engine requires increased coolant flow to maintain proper temperature of internal components. If a high flow rate water pump is used to provide a high coolant flow rate under severe conditions to prevent engine overheating, the amount of coolant flow will be excessive under normal operating conditions. Parasitic losses occur in a cooling system having excessive coolant flow through the engine.
The present invention minimizes parasitic losses in a cooling system by using a system bypass to reduce coolant flow through the coolant jacket of an engine. The system bypass allows coolant to bypass the engine and flow directly from the outlet of the water pump in to the inlet of the water pump, thereby forming a recirculating loop. A diverter valve in the system bypass can selectively increase or decrease coolant flow through engine coolant jacket without changing the output of the water pump.
A control module detects coolant temperature, fuel flow rate, air flow rate, and engine knock information. As these values change, the control module adjusts the diverter valve accordingly to maintain proper engine cooling. The control module actuates the diverter to recirculate a greater amount of coolant flow to the water pump, when the engine is operating below optimal temperature. As the engine reaches optimal operating temperature, a conventional thermostat directs engine coolant flow to a radiator to maintain a desired coolant temperature. The control module actuates the diverter to control coolant flow between the system bypass and the coolant jacket of the engine to maintain needed coolant flow.
Under severe conditions such as high speed driving, rapid acceleration, or towing, additional engine heat is produced. As a result of the additional heat production, the control module actuates the diverter valve to increase coolant flow to the coolant jacket to maintain optimal engine operating conditions. As conditions change where engine heat production is reduced, the control module actuates the diverter valve to divert additional coolant to the system bypass instead of the coolant jacket to increase cooling system efficiency and thereby reduce parasitic losses in the system.